Sonoita climate

Sonoita Frost Dates and Growing Season

NOAA 1991-2020 normals for Sonoita, 0.2 km from Sonoita, elevation 4895 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sonoita. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around March 28 and the first fall freeze around November 21, a growing season of about 237 days.

Median at 36°F
last April 16, first November 9
Median at 32°F
last March 28, first November 21
Median at 28°F
last March 1, first December 2

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 4Apr 29Apr 24Apr 20Apr 16Apr 11Apr 7Apr 3Mar 26
32°FApr 21Apr 13Apr 7Apr 2Mar 28Mar 22Mar 17Mar 10Mar 1
28°FApr 4Mar 22Mar 13Mar 7Mar 1Feb 25Feb 17Feb 6Jan 29
24°FMar 3Feb 23Feb 14Feb 8Feb 2Jan 25Jan 12Jan 5Dec 25
20°FFeb 22Feb 12Feb 4Jan 29Jan 19Jan 9Jan 2Dec 27Dec 12
16°FFeb 17Feb 9Feb 4Jan 29Jan 21Jan 8Jan 4Dec 30Dec 19

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FOct 25Oct 31Nov 2Nov 6Nov 9Nov 13Nov 16Nov 19Nov 25
32°FNov 5Nov 11Nov 15Nov 18Nov 21Nov 24Nov 27Dec 1Dec 7
28°FNov 16Nov 22Nov 25Nov 29Dec 2Dec 7Dec 11Dec 16Dec 23
24°FNov 27Dec 3Dec 8Dec 14Dec 20Dec 26Jan 1Jan 9Jan 26
20°FDec 5Dec 15Dec 23Dec 29Jan 3Jan 9Jan 19Jan 29Feb 12
16°FDec 17Dec 27Jan 2Jan 5Jan 14Jan 26Feb 1Feb 7Feb 17

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F231223217211206202197191183
32°F268256248243237231224217207
28°F313299288281273265258250237
24°F361348339331322313305295279
20°F365365365365365358348335316
16°F365365365365365365365365357

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
94% of years
20°F or colder
51% of years
16°F or colder
14% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
2,639
Cooling degree days, base 65°F
1,407
Growing degree days, base 40°F
7,968
Growing degree days, base 45°F
6,286
Growing degree days, base 50°F
4,761
Growing degree days, base 55°F
3,437
Growing degree days, base 60°F
2,316

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January572041
February476066
March3621154
April1878277
May57107515
June1328776
July0369834
August0313778
September4217663
October8660443
November3145177
December581037

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 0.2 km from Sonoita. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00027990 (Sonoita). Public domain.